Capture single image

karl

Hello,
I am trying to capture a single image on request using the V3 api, but it's not working. If I set the commands
this->rgbCamera->initialControl.setCaptureIntent(dai::CameraControl::CaptureIntent::STILL_CAPTURE);

I keep getting a continuous video stream, sending a command later on for setCaptureStill(true)does nothing.

If I try to do initialControl.setStopStreaming(); it stops getting any messages at all! What is the proposed way to do this in the V3 api?

Thanks

OskarSonc

Hey karl - In v3, CaptureIntent::STILL_CAPTURE / setCaptureStill(true) don’t gate the stream (they’re control/3A hints). setStopStreaming() stops the camera completely until setStartStreaming().

For “single image on request” on v3, the current way is to grab one frame from the strea. Here is our premade example for that:
https://docs.luxonis.com/software-v3/depthai/examples/camera/camera_still_max_res/

Thanks,
Oskar

karl

Hi I got the single capture working but now I am having issue manually closing the pipeline/device, I get a dai::MessageQueue::QueueException when I try to stop()/close() the pipeline or the device. I am assuming this has something to do with the blocking wait on the queues in the device, is this a known issue?

OskarSonc

Hey karl - that’s expected if a thread is blocked in queue.get() while you stop/close the pipeline/device the queue teardown triggers dai::MessageQueue::QueueException. Use tryGet() (or get() with timeout) + a stop flag, stop/join your reader threads before closing, or just catch QueueException and treat it as normal shutdown.

Thanks,
Oskar

karl

But then how is it cleaned up in the example <https://docs.luxonis.com/software-v3/depthai/examples/camera/camera_still_max_res/ ](https://docs.luxonis.com/software-v3/depthai/examples/camera/camera_still_max_res/)? Does this example application always throw before exiting?

In my case I wait for the thread derived from dai::node::CustomThreadedNode<> to stop, reset the sharedptr to it, also I close all queues from the device side and reset the sharedptr. I have no blocking send/wait. Still get the crash from the pipeline.

karl

I updated the code to exit from the device script, and I stop the pipeline afterwards, it's still crashing with dai::MessageQueue::QueueException

karl

So I tried with a modified version of the example in the link, it still has the same issue

int main() {
  // Create device
  std::shared_ptr<dai::Device> device = std::make_shared<dai::Device>();

  // Create pipeline
  dai::Pipeline pipeline(device);

  // Create nodes
  auto cam = pipeline.create<dai::node::Camera>()->build(dai::CameraBoardSocket::CAM_A);
  auto camQIn = cam->inputControl.createInputQueue();

  // In some cases (IMX586), this requires an 8k screen to be able to see the full resolution at once
  auto streamHighestRes = cam->requestFullResolutionOutput();

  // Create script node for still capture
  auto script = pipeline.create<dai::node::Script>();
  streamHighestRes->link(script->inputs["in"]);

  // Current workaround for OAK4 cameras, as Camera node doesn't yet support "still" frame capture
  script->setScript(R"(
        while True:
            message = node.inputs["in"].tryGet()
            if message is not None:
              trigger = node.inputs["trigger"].tryGet()
              if trigger is not None:
                  node.warn("Trigger received!")
                  node.io["highest_res"].trySend(message)
    )");

  // If 8k, we can only have 1 output stream, so we need to use ImageManip to downscale
  auto imgManip = pipeline.create<dai::node::ImageManip>();
  streamHighestRes->link(imgManip->inputImage);
  imgManip->initialConfig->setOutputSize(1333, 1000);
  imgManip->setMaxOutputFrameSize(1333 * 1000 * 3);
  auto downscaledResQ = imgManip->out.createOutputQueue();

  auto highestResQ = script->outputs["highest_res"].createOutputQueue();
  auto qTrigger = script->inputs["trigger"].createInputQueue();

  // Start pipeline
  pipeline.start();
  std::cout << "To capture an image, press 'c'" << std::endl;
  int input;
  while (true) {
    auto imgHd = downscaledResQ->get<dai::ImgFrame>();
    if (imgHd == nullptr) continue;
    std::cin >> input;
    if (input == 1)
      break;
    else if (input == 2)
      qTrigger->send(std::make_shared<dai::Buffer>());
      // Send a trigger message to the Script node
    

    if (highestResQ->has()) {
      auto highresImg = highestResQ->tryGet<dai::ImgFrame>();
    }
  }
  return 0;
}

I still get exceptions thrown

Exception thrown at 0x00007FF868CB5369 in test-oak.exe: Microsoft C++ exception: dai::MessageQueue::QueueException at memory location 0x00000025E5CFF270.
Exception thrown at 0x00007FF868CB5369 in test-oak.exe: Microsoft C++ exception: dai::MessageQueue::QueueException at memory location 0x00000025E5EFE500.
Exception thrown at 0x00007FF868CB5369 in test-oak.exe: Microsoft C++ exception: dai::MessageQueue::QueueException at memory location 0x00000025E5DFE220.
Exception thrown at 0x00007FF868CB5369 in test-oak.exe: Microsoft C++ exception: dai::MessageQueue::QueueException at memory location 0x00000025E5BFF3C0.
The thread 20296 has exited with code 0 (0x0).
The thread 20652 has exited with code 0 (0x0).
The thread 8268 has exited with code 0 (0x0).
The thread 20832 has exited with code 0 (0x0).
Exception thrown at 0x00007FF868CB5369 in test-oak.exe: Microsoft C++ exception: dai::MessageQueue::QueueException at memory location 0x00000025E60FE5E8.
The thread 21948 has exited with code 0 (0x0).
The thread 'EventRead00Thr' (19576) has exited with code 0 (0x0).
Exception thrown at 0x00007FF868CB5369 in test-oak.exe: Microsoft C++ exception: dai::XLinkReadError at memory location 0x00000025E59FF070.
Exception thrown at 0x00007FF868CB5369 in test-oak.exe: Microsoft C++ exception: dai::XLinkReadError at memory location 0x00000025E5FFEAC0.
Exception thrown at 0x00007FF868CB5369 in test-oak.exe: Microsoft C++ exception: dai::XLinkReadError at memory location 0x00000025E5AFE940.

Im not sure its such a good idea to just catch all exceptions coming from your runtime and ignore them, is there truly no other way?

OskarSonc

karl - hm did you try running the stock "Camera still image at max resolution" and pressing "q" to exit?
I figure you are running this in VSC with debugger on? Also you could disable “Break on thrown” for C++ exceptions (and optionally add these to “ignored”): dai::MessageQueue::QueueException, dai::XLinkReadError.
Also are you on RVC2 or RVC4?

karl

Yes apparently it's just the project settings to stop on all exceptions, if I remove the setting it no longer crashes the project, but the exceptions do still occur and are somehow handled internally. Is it safe to leave it like this?

OskarSonc

karl - yes, should be okay, since exit codes are all 0.